Some wireless systems may use multiple antennas, such as a multiple-input, multiple-output (MIMO) system. MIMO systems may use multiple antennas at both the transmitter and receiver. MIMO systems may transmit multiple data streams over the multiple antennas to provide spatial diversity to the overall communication signal. Spatial diversity may improve performance of a wireless system, such as providing greater range or throughput for the system.
Some wireless system may also use multiple carriers. A multicarrier system is typically characterized by a frequency band associated with a communication channel that is divided into a number of smaller sub-bands, sometimes referred to as subcarriers. Examples of multicarrier systems may include Orthogonal Frequency Division Multiplexing (OFDM) systems and Discrete Multi-tone (DMT) systems. A multicarrier system may communicate information by dividing the informational content into symbols, and then transmitting the symbols in parallel using a number of subcarriers. Interleaving symbols across subcarriers may provide a form of frequency diversity, which may also improve performance of the system.
The use of spatial diversity or frequency diversity may improve certain aspects of a wireless system. There are limitations, however, to the amount of spatial diversity or frequency diversity available to any given system. Consequently, techniques to improve spatial diversity and/or frequency diversity may increase performance of a wireless system.